A loudspeaker drive unit typically includes a diaphragm (also known as a cone), a chassis (also known as a basket or frame), a voice coil and a driver magnet. The diaphragm is typically attached to the chassis via a flexible suspension of some sort. For example, the diaphragm may be attached to the chassis by a two-part suspension comprising (i) a spider, typically a corrugated disk of flexible material which joins the centre of the diaphragm/voice-coil to the chassis and (ii) a surround, typically a ring of flexible material which joins the outer circumference of the diaphragm to the chassis. The voice coil is typically attached to the diaphragm so that in use an electrical current is applied to the voice coil generating an electromagnetic field which interacts with the magnetic field of the driver magnet thereby causing the voice coil and consequently the diaphragm to move.
In order to maintain sound quality in use, when the drive unit is installed in a loudspeaker enclosure such as a loudspeaker cabinet, it is desirable for the drive unit to produce controlled vibration in the diaphragm whilst minimising, or otherwise controlling, unwanted vibration in the other elements of the loudspeaker drive unit and enclosure. One way in which such undesirable vibrations in the enclosure can be reduced is to decouple the drive unit from the enclosure by means of a suspension system that allows for mounting of the chassis to the enclosure in such a way as to reduce the transmission of vibration in the chassis to the enclosure. The chassis can thus be decoupled from the enclosure. Such a solution suffers from the problem however that without a rigid connection between chassis and enclosure there tends to be greater vibration in the chassis than would otherwise be the case. This can result in a deterioration in the acoustic performance of the drive unit because, for example, the front ring of the chassis is more prone to vibrate undesirably and thus radiate unwanted sound colouring or otherwise distorting the acoustic response of the loudspeaker.
The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved loudspeaker drive unit. Alternatively or additionally, the present invention seeks to provide a loudspeaker drive unit which can provide improved acoustic performance.